Abstract: The centrifuge tests and numerical simulations are carried out to explore the small-displacement behavior of 9 m-diameter offshore wind power large-scale monopiles with various embedment depths. The results show that as the embedment depth increases, the rotation center gradually moves downward, and the nonlinear characteristics of lateral displacement and rotation angle distributions along piles are gradually enhanced. The difference among p-y curves of monopiles with various embedment depths gradually increases with depth. In terms of trend, the p-y curve changes from convex to concave with the increasing embedment depth. In terms of magnitude, the initial secant modulus at the same depth can differ by 4 times. It can be explained as follows: when the same lateral displacement occurs at the same depth, the monopiles with relatively smaller embedment depths show smaller influence zones of both radial and circumferential displacements in the surrounding soils, and then the soil strain is larger, which eventually contributes to a larger horizontal resistance on piles. The research results help to deepen the understanding of the load-transfer mechanisms of large-diameter monopiles, and to provide a theoretical basis for the optimization of associated design approaches.